The lesser horseshoe bat Rhinolophus hipposideros feeds regularly throughout the winter across its British and Irish range. During winter 1995/96 and 1998/99, in Cornwall R. hipposideros fed mainly on dipteran flies in the families Tipulidae/Trichoceridae, Sphaeroceridae and Mycetophilidae. Differences in dietary composition were found across the British and Irish range of R. hipposideros in winter, and these probably relate to local habitat differences. Nevertheless, across sites Tipulidae/Trichoceridae were always the most frequently eaten prey in winter, with Mycetophilidae and Anisopodidae also eaten frequently. The ecology of the important prey families indicated the value of damp woodland with decaying wood and grazing animals, particularly cattle, for the winter foraging of R. hipposideros.